1. Technical Field of the Invention
The present invention generally relates to signaling protocols in telecommunications networks. More particularly, and not by way of any limitation, the present invention is directed to a partitionable state machine arrangement for implementing a high speed link (HSL) at a network element capable of supporting multiple connections using a generic state machine (GSM) architecture.
2. Description of Related Art
Out-of-band signaling establishes a separate channel for the exchange of signaling information between call component nodes in order to set up, maintain and service a call in a telephony network. Such channels, called signaling links, are used to carry all the necessary signaling messages between the nodes. Thus, for example, when a call is placed, the dialed digits, trunk selected, and other pertinent information are sent between the network elements using their signaling links, rather than the trunks which will ultimately carry the bearer traffic, i.e., conversation.
Out-of-band signaling has several advantages that make it more desirable than traditional in-band signaling. First, it allows for the transport of more data at higher speeds than multi-frequency (MF) outpulsing used in the telephony networks of yore. Also, because of separate trunks and links, signaling can be done at any time in the entire duration of the call, not just at the beginning. Furthermore, out-of-band signaling enables signaling to network elements to which there is no direct trunk connection.
Signaling System No. 7 (SS7) provides a packet-based signaling architecture that has become the out-of-band signaling scheme of choice between telephony networks and between network elements worldwide. Three essential components are defined in a signaling network based on SS7 architecture. Signal Switching Points (SSPs) are basically telephone switches equipped with SS7-capable software that terminate signaling links. SSPs generally originate, terminate, or switch calls. Signal Transfer Points (STPs) are the packet switches of the SS7 network. In addition to certain specialized functions, they receive and route incoming signaling messages towards their proper destination. Finally, Service Control Points (SCPs) are databases that provide information necessary for advanced call-processing and Service Logic execution.
As is well known, SS7 signaling architecture, effectuated as a multi-layered protocol that is standardized under such organizations as the American National Standards Institute (ANSI) and the International Telecommunications Union (ITU), is operable as the common “glue” that binds the ubiquitous autonomous networks together so as to provide a “one network” feel that telephone subscribers have come to expect. Furthermore, SS7 signaling has made it possible to provision a host of advanced services (or, Value-added Services) based on Intelligent Network (IN)/Advanced Intelligent Network (AIN) architectures in both wireless and wireline telecommunications networks.
The exponential increase in the number of local telephone lines, mobile subscribers, pagers, fax machines, and other data devices, e.g., computers, Information Appliances, portable and hand-held devices, etc., coupled with deregulation that is occurring worldwide today is driving demand for high capacity STPs which must be easy to maintain, provide full SS7 functionality with so-called “five nines” operational availability (i.e., 99.999% uptime), and additionally provide the capability to support future functionality or features as the need arises. Further, as the subscriber demand for more service options proliferates, an evolution is taking place in the telecommunications industry to integrate IN/AIN-capable SCP functionality within STP nodes.
While it is generally expected that a single platform that supports large-database, high-transaction IN services as well as high-capacity packet switching (hereinafter referred to as a signaling server platform) will reduce equipment costs, reduce network facility costs and other associated costs while increasing economic efficiency, those skilled in the art should readily recognize that several challenges must be overcome before the requisite functionalities can be realized in a suitable network element that satisfies the stringent performance criteria required of telecommunications equipment. First, such a platform must be capable of maintaining a large number of signaling links in order to support the high degree of connectivity required of it. Also, it may be necessary that the signaling links be capable of supporting high transmission rates. As a consequence, the network element must be provided with the capability to efficiently manage the protocol stacks required to implement such high speed signaling links.
Conventional solutions addressing these concerns are beset with numerous shortcomings. Typically, when multiple signaling links based on SS7 architecture are implemented at a node, a plurality of well known SS7 protocol instances are provided, wherein each instance is operable to support a corresponding signaling connection. Further, where hardware implementations are utilized in order to gain performance, the functionality of each layer of the multi-layer protocol instance is effectuated by employing a corresponding state machine in a suitable device realization. It should be appreciated by those skilled in the art that when a large number of signaling link connections are to be maintained, implementing the protocol layer functionality in individual state machines is an unwieldy task because the functionality of each protocol instance needs to be replicated across the entire range of the connections, which thereby gives rise to a large combinatorial matrix of the connections and protocol layers. Further, although the hardware-based state machine implementations are generally superior to software-based implementations in performance, managing the large combinatorial matrices involving the plural link connections and protocol layers negatively impacts link performance in the network node.
In addition, where multiple links are supported in the existing solutions, the signaling protocol stack implementations are confined to managing conventional SS7 protocol instances, with their usual limitation on transmission rates (e.g., 56 kilobits per second) at the physical layer level. That is, they are not adapted to other, higher-transmission-rate capable networking technologies such as, e.g., Asynchronous Transfer Mode (ATM) technology.
Moreover, the current state machine implementations for supporting multi-link capability tend to be sub-optimal in their performance as the number of links increases. This is generally the case even where hardware-optimized solutions are employed. As the number of links increases, not only does the overall management and control of the protocol stack flow become burdensome, tasks geared towards individual layers, e.g., protocol overhead processing, data integrity/validation operations, etc., quickly become highly processor-intensive, whereby state transitions necessary for effectuating a protocol layer service become bogged down.